Methods and apparatus for presenting images

ABSTRACT

An imaging system for presenting an image to a viewer comprises a radiation source configured to generate radiation having different spectral characteristics, and multiple independently operable optical switches configured to selectively transmit, reflect, and/or block radiation from the radiation source to the viewer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention pertains generally to methods and apparatus relating topresenting images.

2. Description of Related Art

Imaging sensors are often the viewing port for complex systems such asseekers, unmanned air vehicles, surveillance and reconnaissance systems,and forward-looking infrared systems. Testing these systems by viewingscenes in the real world can be expensive, time consuming, and limitedin the types of tests that can be conducted due to availability ofspecific scenarios for testing. Less sophisticated optical systems maybe tested with simple target and scene generators, but as moresophisticated systems based on high resolution and multi-spectralimaging sensors are developed, conventional target and scene generationmay not be adequate.

BRIEF SUMMARY OF THE INVENTION

An imaging system for presenting an image to a viewer comprises anelectromagnetic radiation source configured to generate radiation havingmultiple spectral characteristics, and multiple independently operableoptical switches configured to selectively transmit, reflect, and/orblock radiation from the radiation source to the viewer. The viewedimage is made up of pixels defined by the selective operation of theoptical switches with the radiation source. Such an image generator iscapable of creating images with more varied and closer to true spectralcharacteristics than conventional image generators and projectors.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A more complete understanding of the present invention may be derived byreferring to the detailed description and claims when considered inconnection with the figures, wherein like reference numbers refer tosimilar elements throughout the figures, and:

FIG. 1 is a block diagram of an image projection system according tovarious aspects of the present invention;

FIG. 2 is a diagram of a radiation source having a heat source and aheat sink;

FIG. 3 is a diagram of a radiation source having a graded temperatureblack body and one or more non-black body emitters;

FIG. 4 is a diagram of an image projection system according to variousaspects of the present invention;

FIG. 5 is a view of a mirror and a radiation source;

FIG. 6 is a diagram of an optical path for the image projection system;

FIGS. 7A–B are a side cross-section view diagram and a front viewdiagram of a mirror array;

FIG. 8 is a front view diagram of an alternative mirror arrayconfiguration; and

FIG. 9 is a flow diagram of a preparation and presentation process forimage projection.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present specification and accompanying drawing show an exemplaryembodiment by way of illustration and best mode. While these exemplaryembodiments are described, other embodiments may be realized, andlogical, optical, and mechanical changes may be made without departingfrom the spirit and scope of the invention. The detailed description ispresented for purposes of illustration only and not of limitation. Forexample, the steps recited in any of the methods or process descriptionsmay be executed in any suitable order and are not limited to the orderpresented. Further, conventional mechanical and optical aspects andelements of the individual operating components of the systems may notbe described in detail. The representations of the various componentsare intended to represent exemplary functional relationships, positionalrelationships, and/or physical couplings between the various elements.Many alternative or additional functional relationships, physicalrelationships, optical relationships, or physical connections may bepresent in a practical system.

The present invention is described partly in terms of functionalcomponents and various methods. Such functional components may berealized by any number of components configured to perform the specifiedfunctions and achieve the various results. For example, the presentinvention may employ various materials, mirrors, radiation sources,collimators, control systems, shapes, sizes, and weights for variouscomponents, such as optical components, mechanical components, and thelike, which may carry out a variety of functions. In addition, thepresent invention may be practiced in conjunction with any number ofapplications and environments, and the systems described are merelyexemplary applications of the invention. Further, the present inventionmay employ any number of conventional techniques for manufacture,deployment, and the like.

An image projection system according to various aspects of the presentinvention presents images to a viewer, such as an infrared image for usein testing infrared sensors or a video system for providing visualinformation. The image projection system transmits or reflects visiblelight or other radiation, for example using a micro-mirror array, from aradiation source. The radiation source generates radiation havingdifferent optical characteristics, such as different infrared spectraldistributions, at different locations. The image projection systemprojects the scene made up of pixels defined by the selective mirrorreflections of the radiation source to a viewer, such as a human viewer,an imaging sensor, a seeker, or other detection device to provide arealistic scene for test and evaluation of the sensor in the laboratory.

The image projection system may be implemented in any suitable manner.For example, referring to FIG. 1, an exemplary image projection system100 may comprise a radiation source 110 and an optical switch system112. The radiation source 110 generates radiation having differentspectral characteristics, such as color, intensity, frequency, andpolarization. The optical switch system 112 may include multipleindependently operable optical switches to selectively transmit,reflect, or block radiation from the radiation source 110 to the viewer.The characteristics of the radiation provided by the radiation source110, the functions of the optical switch system 112, and/or otheroperations may be controlled by a control system 114.

The radiation source 110 provides radiation that is selectivelytransmitted to the viewer to form the image. The radiation source 110may comprise any suitable system for generating radiation havingdifferent spectral characteristics, such as a white or near-white lightsource, multiple filaments, diodes, or the like, one or more lasers,and/or a heat source having different heat zones or multiple heatingelements at different temperatures. The radiation source 110 suitablypresents radiation having different spectral characteristics atdifferent locations.

For example, an exemplary radiation source 110 comprises an infraredradiation source for providing different spectral distributions and/orintensities of infrared radiation for testing infrared sensors. Inalternative embodiments, the radiation source 110 may emit radiation inthe visible light range and or other spectral regions. The infraredradiation source 110 of the present embodiment has a large dynamic rangefor black and gray body response. The radiation source 110 may beimplemented such that one or more spectral characteristics of thegenerated radiation may vary according to a spatial gradient across theradiation source 110, for example as a black body that varies intemperature from one side to the other.

The apparent temperature of a pixel transmitted to the viewer by theoptical switches 112 varies with the section of the radiation source 110displayed. The temperature of the radiation source 110 of the presentembodiment varies from maximum to minimum from one side of the radiationsource 110 to the other. For example, referring to FIG. 2, the radiationsource 110 may comprise a substantially homogeneous thermal conductor208 with a thermal source 210 on one end and a heat sink 212 on theother. Generating heat at one end and dissipating heat at the otherprovides a substantially linear distribution of temperature about theradiation source 110. Alternatively, the radiation source 110 maycomprise multiple individual heating and cooling elements distributedabout an area to provide an appropriate temperature distribution.

The radiation source 110 may also be further configured to enhanceperformance. For example, the front surface of the radiation source 110may be coated with a Lambertian optically black emitter material, andthe backside is suitably insulated. The radiation source 110 may furtherinclude feedback sensors at various locations on the radiation source110 to provide temperature feedback to the control system 114. Thecontrol system 114 may control the thermal source 210 and the heat sink212 such that the full dynamic range of the scene to be projected iscovered. The apparent temperature of a particular pixel thus becomes afunction of the temperature of that portion of the radiation sourcetransmitted by the particular optical switch.

The radiation source 110 may also include a non-homogeneous thermalconductor or multiple heat sources or other source radiation elements togenerate the desired spectral characteristics. For example, theradiation source 110 may be configured to project pixels with non-blackbody spectral characteristics, such as hot gas emissions spectra tosimulate the jet plume of an air target. Separate sections may be usedto simulate very hot or very cold portions of a scene, such as coldspace or the sun. Referring to FIG. 3, the radiation source 110 mayinclude, for example, one or more non-black-body emitters (NBBEs)310A–D, such as one or more hot gas chambers. By driving the opticalswitch system 112 to display the various NBBE portions of the radiationsource 110, other emitters, such as hot gases, can be accuratelyportrayed.

The radiation source 110 may be configured in any suitable manner tofacilitate selective transmission and/or reflection of radiation to theviewer, such as a panel of heating and cooling elements, a strip, or aring. In the present embodiment, the radiation source 110 comprises anarc forming an area approximating an interior surface of a section of acone. Referring to FIG. 4, the radiation source 110 has a surface thatfaces the optical switch system 112 such that the optical switch system112 is substantially normal to the facing surface of the radiationsource 110. The arc is suitably situated so that the arc issubstantially centered on a central axis 418 passing through the opticalswitch system 112, and all parts of the radiation source 110 emittingsurface are about the same distance from the optical switch system 112.Consequently, an optical switch comprising a rotating canted mirror mayreflect different portions of the radiation source 110 by rotatingaround the central axis 418 (or a nearby substantially parallel axis)without changing azimuthal orientation.

The radiation source 110 may also generate other spectralcharacteristics. For example, the radiation source 110 may generateradiation at a single frequency, but vary in intensity across the arc,allowing a gray scale projection. Further, the radiation source 110 maygenerate different spectral distributions across the transverse area ofthe arc, and different intensities across the radial area of the arc.Thus, by moving in two dimensions instead of one (azimuthal androtational), a mirror may reflect radiation having a larger number ofpossible characteristics, including color, intensity, polarization,and/or the like.

The optical switch system 112 transfers radiation from the radiationsource 110 to the viewer according to signals from the control system114. The optical switch system 112 may comprise any suitable system forselectively reflecting or otherwise transmitting radiation to theviewer. For example, the present optical switch system 112 suitablycomprises multiple optical switches, and each optical switch may beactuated by a switch controller. Each pixel in each frame is suitablyimplemented by one or more optical switches.

The optical switches may comprise any suitable mechanism fortransmitting or reflecting radiation from the radiation source 110 tothe viewer. In the present embodiment, the optical switches areimplemented via an array of mirrors. Each mirror of the arrayindependently moves to select the desired source characteristics fromthe radiation source 110 and reflects it to the viewer. By selectivelyreflecting radiation from various areas of the radiation source 110, theimage projection system 100 provides images that do not persist afterthe image data has changed and the mirror has moved.

Each mirror is a pixel or part of a pixel of the projected scene and isindividually controlled to reflect part of the radiation source 110 tothe viewing area. In the present infrared sensor testing environment, byproperly reflecting a portion of the radiation source 110 correspondingto the desired temperature, it appears to the viewer that the pixel isat the desired temperature. By adjusting the positions of the mirrors, acontinuum of radiation having various optical characteristics may beprovided to the viewer on a pixel-by-pixel basis, resulting in controlof the spectrum of each pixel displayed.

The mirrors may comprise any suitable set of mirrors for reflectingand/or transmitting radiation having the relevant opticalcharacteristics from the radiation source 110 to the viewer, such asmicro-mirrors. The micro-mirrors may comprise any appropriate array ofmicro-mirrors, such as a conventional array of micro-machined mirrors.The mirrors may be any appropriate size. In the present embodiment toallow the desired switching speed, the mirrors are less than about 0.070inches in diameter and may be even smaller.

The mirrors may move in any appropriate manner and in any direction. Inone embodiment, the mirrors move in substantially only one dimension,such as rotationally, to reflect radiation having different opticalcharacteristics to the viewer. For example, referring to FIG. 5, eachmirror 510 may be positioned at an angle with respect to a rotationaxis. The mirror 510 has a built-in tilt such that only the roll axis ofthe mirror 510 requires actuation. As the mirror 510 rotates around therotation axis, the viewing path presented to the viewer sweeps out acone that matches the arc-shaped surface of the variable radiationsource 110. Thus, the angle is selected to reflect different portions ofthe radiation source 110 to the viewer as the mirror 510 rotates. Themirror 510 may select a portion of the radiation source 110 to presentto the viewer depending upon its angular orientation and thus appear atthe temperature of that portion of the radiation source 110. Referringto FIG. 6, with the mirror 510 in the focal plane of the viewer, themirror 510 surface appears as a hole or cavity with the selected portionof the radiation source 110 in the background, thus appearing as auniform source at the average temperature of the section of theradiation source 110 being viewed.

The array of mirrors 510 may be configured in any suitable manner toproject the image to the viewer, and may be configured according to theparticular environment or application. In one embodiment, referring toFIGS. 7A–B, a mirror array 610 comprises a conventional rectangular gridof rows and columns of mirrors or other optical switches (the dotrepresents the mirror's angular position). Alternatively, theconfiguration may be optimized according to mirror shape. For example,referring to FIG. 8, the mirrors 510 may be arranged to accommodatecircular mirrors in a natural stacking order to maximize the fill factoror area occupied by the mirrors 510.

The control system 114 controls one or more mirrors 510 or other opticalswitches. For example, in the present embodiment, referring again toFIG. 7A, the optical switch system 112 includes one or more switchcontrollers, such as mirror controllers 612, each of which sets theappropriate angle of a single mirror 510. The mirror controllers 612 maycontrol the orientation of the mirrors 510 according to any suitabletechnique or technology. For example, in the present embodimentincluding micro-mirrors, the mirror controllers 612 include amicro-electro-mechanical system (MEMS) that rotates each individualmicro-mirror. The MEMS controller rotates the micro-mirror pixel to therequired angle and thus presents the desired portion of the radiationsource 110 to the viewer. In one embodiment, the MEMS controller mayfacilitate indexed stops at selected angles, such as in conjunction witha stepper motor or a torsional ratcheting actuator. In alternativeembodiments, the mirror controller 612 may be configured to move themirror 510 in multiple dimensions, such as in conjunction with anazimuth/elevation approach, like providing an azimuth control on atilted mirror or the like. Fast responses of the mirror controllers 612and mirrors 510 facilitate high data rates, for example allowingtelevision-compatible and higher frame rates. Further, the imageprojection system 100 may be fast enough or synchronized with a viewingsystem to be compatible with both staring and scanning sensors thatoperate near or below conventional video frame rates, though even higherframe rates may be achievable.

Each mirror controller 612 receives information from the control system114 indicating the desired angle position of the mirror 510 for thatframe. The mirror controller 612 drives the mirror 510 to the desiredangle and stabilizes at that position for the necessary dwell period forviewing. The stable dwell period is a period for each frame in which allpixels are stable. Alternatively, the mirror controller 612 may rapidlymove the mirror between positions to generate a composite brightness,gray-scale, color, or other optical characteristics provided to the userfor the particular frame or set of frames.

The optical switch system 112 may include any other appropriate systemsfor the application or environment. For example, in the present infraredapplication, the optical switch system 112 includes a cooler to reducethe temperature of the mirror array so that its infrared emission isnegligible relative to the scene being projected. For projection of aroom temperature scene, the mirror array may be cooled to only a fewdegrees below room temperature. For a space or sky background, however,much lower temperatures are required, which may require additionalsystems, such as encapsulation of the mirror array in a vacuum dewar tomaintain temperature and prevent condensation. The cooler may comprise athermo-electric cooler, a pour-fill liquid nitrogen chamber, a JouleThompson cooler, a closed cycled cooler, or other appropriate cooler.

Referring again to FIGS. 1 and 4, the control system 114 controls theoperation of the image projection system 100 according to image data.For example, the image projection system 100 of the present embodimentreceives image data from a data source 116. The image data may compriseany suitable data relating to an image or series of images, such as atelevision signal, computer-generated image data, a signal correspondingto a motion picture in visible, infrared, or other radiation, or otherdata corresponding to an image. The control system 114 controls theoperation of various components of the image projection system 100, suchas the radiation source 110 and the optical switch system 112, accordingto the image data.

The control system 114 may comprise any suitable elements and beconfigured in any suitable manner to generate the images according tothe image data. For example, the control system 114 may include acomputer to analyze the image data for the values required by theradiation source 110 to generate the image. In addition, the controlsystem 114 may convert the image data to control signals for controllingthe optical switch system 112 to reflect radiation from different partsof the radiation source 110 to generate the desired image.

In the present exemplary embodiment, the control system 114 includes anexecutive controller 410, a radiation source controller 412, and anoptical switch system controller 414. The various controllers maycomprise physically separate systems, or may be integrated into one ormore systems. The executive controller 410 analyzes the image data todetermine the spectral characteristics and source temperatures requiredto generate the image. The required temperature and spectra areidentified to the radiation source controller 412, which drives theradiation source 110 to generate the appropriate spectralcharacteristics. The executive controller 410 also maps the locations onthe radiation source 110 corresponding to particular spectralcharacteristics, and converts the image data to positions for thevarious mirrors 510 to reflect the appropriate spectral characteristicsto the viewer. The positions for the various mirrors 510 are transferredto the optical switch system controller 414, which adjusts the positionsof the mirrors 510 or other optical switches.

For example, the executive controller 410 of the present embodimentsuitably prepares and executes a motion picture presentation. Theexecutive controller 410 receives the image data and prepares data foruse by the radiation source controller 412 and the optical switch systemcontroller 414. In particular, the executive controller 410 of thepresent embodiment initially receives the entire set of image data forthe motion picture and analyzes the data for the various spectralcharacteristics in the data. For example, the executive controller 410may identify the maximum and minimum spectral frequencies, the specificspectral frequencies, an average spectral frequency represented by theimage data, or any other information that may be useful to the radiationsource controller 412 or other systems. The spectral information maythen be provided to the radiation source controller 412, directly to theradiation source 110, or other suitable systems. In alternativeembodiments, the executive controller 410 may omit this process, forexample in an image projection system 100 using a static radiationsource 110 with a constant spectral range or using a rapidly respondingradiation source 110, or if the image data already includes the relevantinformation.

The executive controller 410 may also map angular representations forthe mirrors 510 to reflect selected spectral distributions, intensities,and/or other spectral characteristics. For example, the executivecontroller 410 may initially identify which portions of the radiationsource 110 are to emit particular spectral distributions and/orintensities. The executive controller 410 may also identify mirrorangles at which mirrors 510 reflect various spectral distributionsand/or intensities from the radiation source 110 to the viewer. Theangle information may be stored, such as in a lookup table.

The executive controller 410 further analyzes the image data to convertordinary image data, such as pixel colors and intensities, to angularinformation for moving the mirrors in the mirror system 112. Conversionof the image data may be performed according to any appropriate process,and may be performed prior to presentation or at run time. For example,in the present embodiment, the image data may comprise a series offrames including pixel data, such as pixel black body temperature andother spectral characteristics, for each pixel for each frame. Theexecutive controller 410 suitably converts the image data for each pixelfor each frame into an angular position for reflecting the portion ofthe radiation source 110 emitting the appropriate frequency to theviewer. The converted angle data may then be stored for presentation orprovided frame-by-frame to the optical switch system controller 414 forpresentation.

The radiation source controller 412 controls the radiation source 110 togenerate the appropriate spectral distributions, intensities, and/orother spectral characteristics for the image presentation. The radiationsource controller 412 may comprise any suitable system for controllingthe operation of the radiation source 110, and may control the radiationsource 110 according to any suitable criteria and processes. In thepresent embodiment, the radiation source controller 412 receives thespectral information from the executive controller 410 and controls theradiation source 110 to generate radiation having the required spectralcharacteristics. The radiation source controller 412 may comprise anysuitable system for controlling the radiation source 110, such as one ormore digital electronics and drivers configured to drive the thermalsource 210 and heat sink 212 of the radiation source 110 to the requiredtemperatures. The radiation source controller 412 may also receiveinformation from feedback sensors on the radiation source 110 to controlthe operation of the radiation source 110.

The optical switch system controller 414 controls the states of theswitches in the optical switch system 112, such as the mirrors 510. Theoptical switch system controller 414 may comprise any suitable systemfor controlling the optical switch system 112, such as digitalelectronics and drivers that receive pixel angle information from theexecutive controller 410 and distribute it to the mirrors 510 to allowtimely presentation. In the present embodiment, the optical switchsystem controller 414 functions as a video processor for receivingframes of angular data from the executive controller 410 and driving thevarious pixel mirrors 510 of the optical switch system 112 according tothe signals to generate the desired image. The optical switch systemcontroller 414 may operate according to any suitable configuration,however, such as asynchronously directly addressing particular pixels toadjust the pixel reflection to a different location on the radiationsource 110. The mirror controllers 612 may be provided with signalstorage at each pixel site such that mirror angle signal may be readinto pixels asynchronously before the next frame. This allows allmirrors of the array to move to the desired orientation simultaneously,thus, reducing the overall time required for switching.

The radiation from the optical switch system 112 is transmitted to theviewer or a viewing system. The radiation may be viewed directly or, asin the present embodiment, transmitted via an optical transfer system118 (FIG. 1). The optical transfer system 118 may perform anyappropriate functions, such as collimating, focusing, or filtering theradiation. For example, in the present embodiment, the radiation istransmitted to the viewer through a housing 415 via a refraction modecollimator 416 (FIG. 4). The image projection system 100 may include anyother suitable optics and other components in the optical path of thesystem.

In operation, the image projection system 100 prepares for thepresentation and then presents the image data. The preparation processmay comprise any suitable process for setting up the image projectionsystem 100 for the presentation, such as programming the radiationsource 110 to generate the appropriate optical characteristics andgenerating the mirror angles for each pixel in each frame of data. Forexample, referring to FIG. 9, the executive controller 410 initiallyreceives the image data from the data source (910). The executivecontroller 410 analyzes the image data for any relevant characteristicsfor the presentation (912), such as the optical characteristics requiredto be generated by the radiation source 110. If the radiation source 110is to be programmed, the executive controller 410 may provide therelevant information to the radiation source controller 412, which maythen drive the radiation source 110 accordingly to emit the appropriateradiation (914). In addition, the executive controller 410 may map theareas of the radiation source 110 corresponding to particular opticalcharacteristics (916) and associate each area with an angular positionfor the mirrors 510 (918). Thus, the desired radiation source 110characteristics can be entered to the radiation source 110 and theirlocations programmed, resulting in pixel spectral characteristics withfew limits.

The executive controller 410 may also convert the image data to mirrorpositions (920). For example, in the present embodiment, the executivecontroller 410 analyzes each pixel in each frame for the pixel blackbody temperature and/or other spectral characteristics. The executivecontroller 410 may then look up the desired frequency on the map of theradiation source 110 and arrive at a desired angle for the mirror 510for the corresponding pixel. The executive controller 410 may furthercompensate the angle for any suitable factors that may affect theradiation source 110 or the mirror system 112, such as to remove displaynon-uniformity due to imperfections in MEMS and mirror fabrication. Theresulting angles for the pixels for each frame may then be stored.

To begin the presentation, the executive controller 410 provides theconverted image data to the optical switch system controller 412. Theoptical switch system controller 412 drives the mirrors 510 at theappropriate data rate. For each frame, the optical switch systemcontroller 412 provides the angular position data for each pixel to theindividual mirror controllers 612 (922), which rotate the mirrors 510 tothe appropriate positions and hold them in position (924). The mirrors510 reflect radiation from the selected area of the radiation source 110to the optical transfer system 118, which collimates and/or otherwiseprocesses the radiation for transfer to the viewer. To present a stableimage, the mirror position may be maintained for a selected dwell period(926). The process is repeated for each frame until the last frame istransmitted (928).

The image projected by the image projection system 100 may not be fullyconstant when the mirrors are being adjusted. If desired, any suitablesolution may be implemented to address any resulting problems. Forexample, if the viewer comprises a sensor being tested, the sensor maybe synchronized with the mirror adjustment periods of the imageprojection system 100 to acquire data only during the stable dwellperiods. Alternatively, data collected by the sensor during the mirroradjustment periods may be discarded from the data collection, leavingonly data acquired during stable dwell periods. Also, a radiationchopper may be used to blank viewing while the mirrors are moving if theviewing sensor integrates the signal continuously as does the human eye.

Although the description above contains many details, these should notbe construed as limiting the scope of the invention but as merelyproviding illustrations of some of the exemplary embodiments of thisinvention. The scope of the present invention fully encompasses otherembodiments, and is accordingly to be limited by nothing other than theappended claims, in which reference to an element in the singular is notintended to mean “one and only one” unless explicitly so stated, butrather “one or more.” All structural, optical, material, and functionalequivalents to the elements of the above-described exemplary embodimentsare expressly incorporated by reference and are intended, unlessotherwise specified, to be encompassed by the claims. Moreover, it isnot necessary for a device or method to address each and every problemsought to be solved by the present invention for it to be encompassed bythe present claims. Furthermore, no element, component, or method stepin the present disclosure is intended to be dedicated to the publicregardless of whether the element, component, or method step isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. 112, sixth paragraph, unless theelement is expressly recited using the phrase “means for.” The terms“comprises”, “comprising”, or any other variation, are intended to covera non-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

1. An imaging system for presenting an image to a viewer, comprising: aninfrared radiation source configured to generate infrared radiation atmultiple spectral distributions, wherein the infrared radiation sourcegenerates a first spectral distribution at a first location and a secondspectral distribution at a second location; and multiple independentlymovable mirrors, wherein at least one mirror is configured to reflectradiation from the first location and the second location of theinfrared radiation source to the viewer.
 2. An imaging system accordingto claim 1, wherein the at least one mirror moves in substantially onlyone dimension.
 3. An imaging system according to claim 1, wherein the atleast one mirror moves substantially only rotationally around an axisthat is substantially normal to a plane defined by the movable mirrors.4. An imaging system according to claim 1, wherein the radiation sourcecomprises multiple electrically resistive elements.
 5. An imaging systemaccording to claim 1, wherein the radiation source generates a gradientof temperatures in a selected direction.
 6. An imaging system accordingto claim 1, further comprising a control system connected to the mirror,wherein the control system is configured to: receive image data; andconvert the image data to mirror positions.
 7. An imaging systemaccording to claim 1, wherein the radiation source comprises at least aportion of an arc, wherein the arc defines a plane substantially normalto a path of the radiation transmitted to the mirrors.
 8. An imagingsystem according to claim 1, wherein: the radiation source comprises anat least partially arc-shaped surface facing the mirrors, wherein thearc-shaped surface defines a plane substantially normal to a path of theradiation transmitted to the mirrors; and the mirrors comprise asubstantially planar mirror array, wherein each mirror in the array ismounted at an angle to an axis to reflect different positions on theradiation source as the mirror is rotated about the axis.
 9. An imagingsystem for presenting an image to a viewer, comprising: an infraredradiation source configured to generate infrared radiation at a firstspectral distribution at a first location on the infrared radiationsource and at a second spectral distribution at a second location on theinfrared radiation source; multiple independently movable mirrorconfigured to reflect radiation from the infrared radiation source tothe viewer, wherein each mirror reflects radiation from the firstlocation to the viewer when the mirror is in a first position andreflects radiation from the second location to the viewer when themirror is in a second position; and a control system connected to themirror and configured to independently move each mirror between thefirst position and the second position.
 10. An imaging system accordingto claim 9, wherein each of the mirror moves in substantially only onedimension.
 11. An imaging system according to claim 9, wherein each ofthe mirrors moves substantially only rotationally around an axis that issubstantially normal to a plane defined by the movable mirrors.
 12. Animaging system according to claim 9, wherein the radiation sourcecomprises multiple electrically resistive elements.
 13. An imagingsystem according to claim 9, wherein the radiation source forms agradient of temperatures in a selected direction.
 14. An imaging systemaccording to claim 9, wherein the control system is configured to:receive image data; and convert the image data to mirror positions. 15.An imaging system according to claim 9, wherein the radiation sourcecomprises at least a portion of an arc, wherein the arc defines a planesubstantially normal to a path of the radiation transmitted to themirrors.
 16. An imaging system according to claim 9, wherein: theradiation source comprises an at least partially arc-shaped surfacefacing the mirrors, wherein the arc-shaved surface defines a planesubstantially normal to a path of the radiation transmitted to themirrors; and the mirrors comprise a substantially planar mirror array,wherein each mirror in the array is mounted at an angle to an axis toreflect different positions on the radiation source as the mirror isrotated about the axis.
 17. A process for presenting an infrared imageto a viewer, comprising: generating radiation at multiple infraredspectral distributions from a radiation source, wherein generatingradiation at multiple infrared spectral distributions includesgenerating radiation at different infrared spectral distributions atdifferent locations on the radiation source; and selectively reflectingradiation of different spectral distributions from the radiation sourceto the viewer, wherein selectively reflecting radiation from theradiation source to the viewer includes reflecting radiation from thedifferent locations to the viewer.
 18. A process for presenting aninfrared image according to claim 17, wherein reflecting radiation fromdifferent locations comprises moving multiple mirrors.
 19. A process forpresenting an infrared image according to claim 18, wherein movingmultiple mirrors comprises moving the multiple mirrors in substantiallyonly on dimension.
 20. A process for presenting an infrared imageaccording to claim 19, wherein moving the multiple mirrors includesmoving the multiple mirrors around axes that are substantially normal toa plane defined by the movable mirrors.